POWER RANKINGS: Here's who has the best chance at being our next president

In less than 45 days, the first votes of the 2016 presidential primary will be cast.

And heading into the new year, two candidates have firmly entrenched themselves as the front-runners in their respective parties.

On the Republican side, Donald Trump finds himself in perhaps his strongest position yet, leading all national polls and surveys of the early states of New Hampshire, South Carolina, and Nevada. This from a candidate who was largely expected to wane as the summer, let alone fall, went on.

One GOP candidate has bitten the dust over the past month: Sen. Lindsey Graham of South Carolina dropped out of the race on Monday, putting the Republican field at a still robust 13.

In the Democratic primary, meanwhile, Hillary Clinton has continued to cement herself as the clear Democratic front-runner.

Our rankings are based on the Real Clear Politics averages of national polls and those in the first-voting states of New Hampshire, Iowa, and South Carolina. We also factor in candidates' fund-raising prowess and their momentum (or lack thereof) over the past few weeks, especially after each party's debates earlier this month.

Here's a look at where all the candidates stand:

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2016 presidential POWER RANKINGS for 12/24/2015

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POWER RANKINGS: Here's who has the best chance at being our next president

15. George Pataki, former New York governor

From the outset, Pataki has been mostly an afterthought in the race, though he brings a strong résumé as the former governor of the Empire State.

Still, he has barely registered in national or early-state polls. And nothing has been able to jump-start his campaign: not his continued feuding with Trump, and not his performances in the lower-tier, undercard debates.

When Pataki inadvertently referred to Trump as "president" during last week's undercard debate, Trump quipped that he didn't "want his endorsement."

14. Rick Santorum, Republican, former senator from Pennsylvania

It's sometimes easy to forget that Santorum won 11 states in his 2012 primary matchup with Mitt Romney, the eventual Republican nominee — including the Iowa caucus.

That's because he still hasn't even been a blip on the radar in the 2016 race.

He is facing stauncher competition this time around, and he has not solved his biggest problem from 2012: money. He raised less than $400,000 in third-quarter fund-raising and had just more than $200,000 in cash on hand, the kind of money that doesn't bode well for staying power in a crowded field.

The state that provided his biggest win in 2012, Iowa, also hasn't given him the same kind of love. Despite focusing on the Hawkeye State, he still barely registers in polling there, placing 11th in an average of recent polls. He has lingered around that level since he entered the race.

13. Martin O'Malley, Democrat, former Maryland governor

O'Malley has watched as Bernie Sanders has entrenched himself as the progressive alternative to Hillary Clinton, outflanking O'Malley's attempts to outflank Clinton from the left.

Despite a vigorous campaign schedule, O'Malley is still not well known nationally, and he has been unable to boost his poll numbers even in a three-way race.

O'Malley has an accomplished progressive record as governor, with achievements — on immigration, criminal justice, same-sex marriage, and healthcare, among others — that he can legitimately tout to Democratic voters.

But he hasn't been able to break out of the doldrums. His failure to have a breakout-type moment in the third Democratic debate may have sealed his fate in the race.

12. Mike Huckabee, Republican, former Arkansas governor

Huckabee has continued an attempt to endear himself to conservative, evangelical voters. But he's clearly falling short.

The first part of his presumed theoretical path to the nomination — winning Iowa, the state he captured in 2008 — is in serious limbo. He polls just eighth in the Hawkeye State, and he has kept slipping there over the past few months.

This Republican field may be too crowded for a candidate like Huckabee. He is extremely popular with evangelical conservatives, but many of those conservatives look as if they're flocking to candidates such Trump and Sen. Ted Cruz (R-Texas).

11. John Kasich, Republican, Ohio governor

Kasich sits just ninth in polls nationally. And in New Hampshire, where he had surged after investing significant resources, he's polling in just sixth place, behind fellow establishment-minded candidates like Gov. Chris Christie of New Jersey and former Gov. Jeb Bush of Florida.

Those who talk up Kasich believe he is a Christie-type without the baggage of the past year and a half — that is, a successful governor with a record to point to and clear bipartisan appeal. He also has a plethora of experience from serving nearly two decades in Congress, including foreign-policy areas and his time as chair of the US House Budget Committee.

But that same bipartisan brand could hurt Kasich with the GOP base. He is to the left of most GOP candidates on immigration reform, and he expanded the federal Medicaid program under the Affordable Care Act — two issues that could doom him with hard-line conservatives.

10. Carly Fiorina, Republican, former Hewlett-Packard CEO

Fiorina surged after she stole the show with a stunning performance during the lower-tier Republican debate in August. She then took it to the other candidates on the main stage in September.

But she has since appeared to stumble amid more scrutiny over her record at Hewlett-Packard. She has dipped from her third-place standing in national polls at the height of her climb to just seventh now. And in the latest Republican debate, she was eclipsed by several other candidates on stage.

Still, she has experience as a business executive that few others in the field can point to, and she has been one of Hillary Clinton's fiercest critics.

9. Rand Paul, Republican, senator from Kentucky

Paul is the unconventional candidate of the Republican field. But he has so far been unable to latch on as a clear top-tier candidate.

Paul's advisers have touted some choice polls lately, but the candidate has not been able to break through from his initial plunge over the summer and early fall. Of particular note is his drop in Iowa, where he has fallen from second (9.8%) in July to sixth (3%) now.

His numbers have improved over the past month, however. And in December, Paul delivered perhaps his strongest debate performance yet. He has to hope that builds some momentum — he also has a Senate reelection to start thinking about.

8. Bernie Sanders, Democrat, senator from Vermont

Sanders' campaign shocked political observers by raising more than $27 million in the third quarter, more than any Republican presidential candidate and just $3 million behind Clinton. And he might be on track to raise more than the former secretary of state in 2015's final quarter.

His momentum, and the grassroots support and donations behind it, have evoked comparisons to the rise of Barack Obama, then an Illinois senator, in 2008.

But his time in the intense spotlight looks like it might finally be taking its toll. He has dipped back to fourth place nationally and in Iowa, as scrutiny over his potential as commander in chief has piled up, as he has seen more established candidates like Cruz and Sen. Marco Rubio (R-Florida) rise.

His national poll numbers have dipped about 15 points over the past two months.

6. Chris Christie, Republican, New Jersey governor

Christie is the biggest mover from month to month, jumping from ninth to sixth in our rankings.

Christie has appeared to benefit from an increased focus on national security after the terrorist attacks in Paris and San Bernardino, California, over the past two months.. Lately, he has been surging in the first-in-the-nation primary state of New Hampshire, where he has put in more time than any GOP candidate in the race.

That time has apparently been well spent: He's now nipping at Rubio's heels in what is shaping up to be an establishment race for second place behind Trump. His standing is up from seventh last month, behind fellow establishment-type candidates like Rubio, Bush, and Kasich.

5. Jeb Bush, Republican, former Florida governor

Bush, once viewed as the clear front-runner, has seen Donald Trump sap the momentum he had built after his official campaign announcement in June. His poll numbers have slumped across the board — his 17% national average in July has dipped 12.5 points over the past five months.

Bush has showed, too, that he is a dynamic fundraiser. And he retains significant resources that could prove to be a game-changer in the long haul.

An aligned super PAC raised more than $100 million in the first six months of the year. And Bush entered the home stretch with more cash on hand for the primary than any candidate aside from Cruz and Carson.

4. Marco Rubio, Republican, senator from Florida

Want proof that Rubio's and Cruz's campaigns believe they'll eventually be the final two candidates in the Republican race? Just look at their constant sniping over the past month.

Off strong debate performances, Rubio quickly became a rising establishment favorite for the Republican nomination. But he has stagnated somewhat over the last month, while Cruz has surged ahead of him in Iowa and has tied him in the more establishment-friendly New Hampshire.

One concern is his fundraising: He raised less than $6 million in the third quarter. But deep-pocketed donors are showing signs of potentially rallying around him.

The other concern that's on the minds of many in the Republican political establishment: Which early state can he actually win? Cruz has leapfrogged him in Iowa. Christie might in New Hampshire. And his organization in other states has been viewed as subpar.

3. Ted Cruz, Republican, senator from Texas

Cruz has quietly run an under-the-radar campaign that has put him in sneakily good position to be one of the finalists for the nomination.

It's finally starting to pay off — in a big way.

Cruz is amid the top tier of GOP polling, and he has surged to a lead over Trump in Iowa. He has jumped 7 points nationally, 15 points in Iowa, and 8 points in South Carolina over the past month.

Meanwhile, his eye-popping fundraising numbers mean that he will most likely be in the race for the long haul. He raised the third-most of any Republican candidate last quarter, and he had the most cash on hand entering the home stretch.

Cruz inspires a flood of enthusiasm among the GOP base, and he may be the best-positioned candidate from within the political sphere to back up the notion that he's not a typical politician, that he is the outsider the base wants despite his day job in Washington.

2. Donald Trump, Republican, businessman

Trump has lit the political world on fire since his entry into the race early this summer. And he has showed surprising staying power — we're now on month No. 7 of the Trump show.

The summer of Trump, which turned into the autumn of Trump, is about to become the winter of Trump. And he's in perhaps his strongest position yet, as his national poll standing has climbed 6 points over the past month.

There's a clear appetite among Republican primary voters for someone like Trump, from the moment he entered the race to controversy surrounding his position on illegal immigration. Business Insider discovered more of that when we followed him on the trail for a week last month.

1. Hillary Clinton, Democrat, former secretary of state

Clinton is No. 1 here because she has proved formidable in polling and fundraising. And she clearly looks to be able to glide to the nomination, perhaps early on in the voting process, because of the slimmer competition on the Democratic side.

The summer provided sign after sign of her potential vulnerabilities as a candidate. She saw Sanders sap enthusiasm — and supporters — in key early states like Iowa and, especially, New Hampshire. Her popularity plunged. And she trailed a host of leading Republican candidates in theoretical general-election matchups.

But she has turned things around in the fall. She's up overwhelmingly in Iowa. And in South Carolina,, her near-70% standing is a signal of her "firewall" after the first two voting states.

Meanwhile, she has continued to clean up on the fundraising circuit. She raised more than any other presidential candidate last quarter — almost $30 million — and she holds a whopping $33 million cash on hand.